We are running 3CX 15.5 on our own local Windows Server. The problem we are currently facing is that our IP phones (AAstra 6731i) don't show up in the web client - so it's not possible to trigger calls from the web interface. The phone icon is red and says no phones are connected. Now here comes the interesting part: once a user installs the 3CX Android client and connects to our system the IP phone (AAstra 6731i) shows up in the web client and the MakeCall functions works fine. Even after uninstalling the Android app the IP phone stays as an option. Now I don't wanna force everybody to install the phone app just to make the web client work. Am I missing any settings? Is there an easier way to connect our IP phones to the web client so users can initiate calls from the web interface?